The Shanahans have built their reputations largely on the success of their zone running scheme and in year three, it's time for the system to produce a 1,000-yard rusher in Washington. The Redskins certainly have the candidates, with four runners vying to be the featured back this season.

Aside from the quantity, there is also reason for optimism concerning the quality of the Redskins' backfield rotation. Rookies Roy Helu and Evan Royster displayed plenty of promise last season, with each back producing a pair of 100-yard efforts during the campaign's final five games.

Of the two, Helu is certainly the more dynamic. He can be inconsistent between the tackles, but the ex-Nebraska ace possesses legitimate breakaway speed and natural big-play capability.

Royster has a stronger initial burst, which is a definite asset for zone runners who must make quick decisions at the handoff. He is better between the tackles than Helu and has genuine workhorse potential.

However, as promising as the young duo appear to be, this author has believed for a while that veteran Tim Hightower presents the team with the most. What's more, a recent ProFootballWeekly.com report indicated that Hightower might still be the preferred option.

Despite having his debut season in D.C. ruined by a serious ACL injury, Hightower has recovered and offers the combination of quickness and power the Redskins need. The 26-year-old was impressing before his spell on the sidelines, and he has the size and vision to excel as a zone runner.

Sixth-round draft pick Alfred Morris is the wild card in the pack. The former Florida Atlantic standout is a natural cutback runner with excellent leverage and deceptive quickness. He could vault to the top of the pecking order with a strong training camp.

Shanahan has the weapons to get the most out of his zone-based system, and the scheme can cause havoc in the NFC East. One of its signature plays is the stretch run. With the tight end sent in motion to the left, the Redskins use three blockers to attack laterally and seal the edge on that side.

The runner follows this trio with the defense in pursuit. As the blockers push the play to the sideline and begin to turn upfield, the back has a choice of cutback lanes, each of varying degrees. A sharp, quick cut to the inside is enough to defeat pursuit by larger defenders, while linebackers and secondary players are pancaked by mobile linemen moving up the field.

The play can be a dangerous weapon, particularly against the Philadelphia Eagles' Wide 9 alignment. With larger linemen defeated by the cutback, the Eagles will have to rely on middle linebacker DeMeco Ryans one-on-one in the open field.

The stretch play can be equally effective against fellow 4-3 team the New York Giants. Controlling the clock in NFC East will be crucial for the Redskins. It will help limit the exposure of a suspect secondary to quarterbacks Eli Manning, Michael Vick and Tony Romo.

Shanahan needs his famed running scheme working at a high level this season. Emphasising the ground game from the start of the campaign will make a big difference in the win-loss column.